Process of cyanoethylating native cotton fibers with an aqueous emulsion of sodium hydroxide and acrylonitrile



June 24, 1958 Filed Oct. 10, 1955 FIG. I

J. COMPTON ETAL 2,840,446 PROCESS OF CYANOETHYLATING NATIVE COTTONFIBERS WITH AN AQUEOUS EMULSION OF SODIUM HYDROXIDE AND ACRYLONITRILE 6Sheets-Sheet 1 l l I S '2 I If "'5 .5

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ATTORNEYS June 24, 19548 J. COMPTON ETAL PROCESS OF CYANOETHYLATINGNATIVE COTTON FIBERS WITH AN AQUEOUS EMULSION OF SODIUM HYDROXIDE ANDACRYLONITRILE 6 Sheets-Sheet I 2 Filed Oct. 10. 1955 T cozuuzu aoz vT coouom vT :o o ut 200 V O 7 On ON 0 own ud mm m 03H INVENTORS.

5 7 MW 5 mm P E M MW o CM ,0 s w K MA CM M June 24, 1958 Filed Oct. 10,1955 FIG. 3

69 6. .Ol4lb. N0 OH/lb. Cotton 63 0. O O 69C. .O2llb. No OH/lb. Cotton63" c 0 IO 9* Solubihty Llmlf H O In J. COMPTON EI'AL 2,840,446PROCESSOF-CYANOETHYLATING NATIVE COTTON FIBERS WITH AN AQUEOUS EMULSION0F SODIUM HYDROXIDE AND ACRYLONITRILE 6 Sheets-Sheet 3 Acrylonlfrilo 69C. o 63 C.

25 0. --Cold Circulation -Reoction +Neutrulizotion i Time " id m n 03HINVENTORS. JACK COMPTON BY OATESBY P. JONES ATTORNEYS June 24, 1958 J.COMPTON ETAL 2,840,446

PROCESS OF CYANOETHYLATING NATIVE COTTON FIBERS WITH AN AQUEOUS EMULSIONOF SODIUM HYDROXIDE AND ACRYLONITRILE Filed Oct. 10, 1955 6 Sheets-Sheet4 l I I l I l I I do Lo 0 N [0'0 cow 2: 60 0-0-- as 1 E 1 5 0' II oo 5 II I I l I I I SE *N 0' 0 mm (DID I l l I I F 1D In Q IO N C 21-00%INVENTORS.

JACK COMPTON BYOATESBY P. JONES ATTORNEYS /o 0.0. P. /o N.

n 5 J. COMPTON ETAL 2,840, 46

PROCESS OF CYANOETHYLATING NATIVE COTTON FIBERS WITH AN AQUEOUS EMULSIONOF SODIUM HYDROXIDE AND ACRYLONITRILE Filed Oct. 10, 1955 6 Sheets-Sheet5 FIG. 5

0 N. .OI4Ib. No HO O.D .P. 9 O N. .021 lb. Nu HO O I I I l l x s 8 l0 sa IO H2O H2O INVENTORS.

JACK COMPTON OATESBY P. JONES fimwmfimmfi a ATTORNEYS Patented PROCESSOF CYANOETHYLATING NATIVE COT- TON FIBERS WITH AN AQUEOUS EMULSION OFSODIUM HYDROXIDE AND ACRYLONI- TRILE Jack Compton, Charlottesville, Va.,and Catesby Perriman Jones, Bethesda, Md., assignors to Institute ofTextile Technology, Charlottesville, Va., a corporation of VirginiaApplication October 10, 1955, Serial No. 539,486 6 Claims. (Cl. 8-120)This invention relates to the reaction of acrylonitrile with cotton andhas for'its object the provision of improved cotton products and aprocess of reacting acrylonitrile with cotton fibers in the form of bulkfibers, yarns, or fabrics to improve the properties of the cotton whilemaintaining the natural structure of the fiber and most of theproperties of ordinary cotton. Our invention pro vides an economical andpractical process of producing our improved cotton products with aminimum loss of chemicals through washing, neutralizing and undesirableby prod-uct formation. The improved cotton products of our invention area partially cyanoethylated cotton, but

they have the-important distinction of retaining the natu ral fibrousform of native cotton fibers, and their crystallinity in'a substantiallyunaltered state.

Several processes'have been proposed heretofore for treating cellulosewith aqueous solutions of sodium hydroxide and ac'rylonitrile-to effectfrom a partial to a complete cyanoethylation, usually resulting in asoluble with but a relatively small proportion of the cellulosegiving:cyanoethylcellulose which; may 'be represented as Cell -OCI- I'CH CNQ We have found that very desirable cotton products can be formedby effecting but,

apartial etheritication of the celluloselmolecule, resulting in butfrom0.006 to 1.0 cyanoethyl group per anhydroglucose unit (equivalent tofrom 0.50 to 6.50% nitrogenbased onQthe: weight ofwcyanoethylatedcotton). In the preferredandmost advantageous embodiment'of ourinvention, we control the conditions to'combine but'from 0.1wto 0.6cyanoethyl group per :anhydroglucose unit.

The following table shows the relationshipbetween the cyanoethylgroups'per anhydro-glucos'e unit nitrogen? content of the cyanoethylatedcotton:

amine Table A Cyanoethyl Percent N Groups per Anhydro- Glucose Unit Ourinvention is specifically directed to the treatment of native cotton.because we aim to produce an im-' proved cotton fiber and cotton ispeculiarly suited to our process. By native cotton we mean naturalcotton Which has neither been changed chemically nor its moleculararrangement altered, although it may have been treated to remove gums,waxes and foreign matter. While cotton is a relatively pure form ofcellulose, the fibers are considered to be formed of threedistinct-types of layers, each having a different physical structure,consisting of amorphous and crystalline components. Mild reactionconditions, such as the preferred cyanoethylation procedure hereindescribed, are required to maintain this, desirable fi'ber structure. Inparticular the relationship between the amorphous and crystallinecomponents. should be maintained. One further characteristic of usefulnative cotton fibers is that the degree of polymerization of thecellulose varies from about 1500 to 4500 and in this respect it. differs.from viscose rayon which a has a degree of polymerization of from about150 to 450. In general, all regenerated cellulosic fi'ber materials haveI a greater proportion of the amorphous component than native cotton andthe crystalline component is characterized by having the mercerizedcellulose molecular ar-v rangement. Cotton thus has a differentstructural arrangement and responds differently than regeneratedeellulose when treated with such chemicals as sodium hydroxide andacrylonitrile. Because of its structure, cotton is a very importanttextile material and our process maintains its structural identity. I

For the cyanoethylation of cotton, we have discovered a very importantrelationship involving the concentration of sodium hydroxide insolution, the amount of sodium hydroxide solution applied to the cottonwith the acrylo nitrile, and the time andtemperature of the reaction ofacrylonitrile with the cotton while in thepresence of a solution ofsodium hydroxide to effect the amount of cyanoethylation necessary toproduce the improved cot-' ton products. We can carry out our process inproduc- 1 ing our. improved cotton products without excessive loss insodium hydroxide. and in lay-product formation which results in a lossof acrylonitrile. I

In accordance with the process of our invention, We apply to thecotton amixture of an aqueous solution of sodium hydroxide and acrylonitrile,which mixture du,r-

ing treatment is in a state of emulsion, and preferably by circulationof the emulsion over'and through the cotton fibers. We may form theemulsion in any suitable way as by mechanically mixing the sodiumhydroxide solution, a surface active agent such as Aerosol-OS (isopropylnapthalene sodium sulfonate), and the acrylonitrile, and apply thisemulsion to the cotton. An emulsion formed by mechanical agitation of anaqueous solution of sodium hydroxide and acrylonitrile may also beusedas is described in our prior application, Serial No. 435,904, filedJune 10, 19 54, now abandoned. The emulsion may be formed, asthereindescribed, by adding the sodium hydroxide solution to theacrylonitrile as it enters a circulating pump which in turn circulatesthe emulsion over the cotton very shortly after the emulsion is formed.1 :Such a mechanically formed emulsion is not stable and separatesquickly. By the use of a surfaceactive agent, such as Aerosol-OS, theemulsion may be Sta" bilized. 2 a

In carrying outour invention, precautions mustbe taken to direct theaddition of the cyanoethyl groups .-CH -CH -.CN without -or with-noappreciable hydrolysis to form carboxyethyl groups In using thelowsodiumhydroxide concentrations in our process we avoid hydrolyzingthe nitrile CN to carboxyl COOI-I andalso neither depolymerizethecrystalline cellulose nor increase the proportiono'fthe amorn ventionare similar in appearance, hand, :and processing 7 characteristics tocotton, but differ prirnarily and significantlyin that they arepermanently resistant to micro organism attack, suchasfcausemildew; moreresistant to wet. an dry h at degradation; more r c p e to m ny dyes ofall classes, including acid dyes; and more resiste ant to abrasion.

In our copendjng appl cation, ,Serial No. 442,762 fi led July 12, 1954,now Patent ,No. 2,786,258, We describe and claimour imwoved fibrous,cottonproduct, and a process for treating cotton Ifibers with aqueoussolutions of sodium hydroxide, preferably in a steeping process, andunder the conditions described herein, but in the process ofithatapplication the presteepedcotton fibers are treated with liquidacrylonitrile containing some water. In the process of our, copendingapplication, Serial No. 435,903, filed June .10, 1954, now Patent No.

2,786,735, the'presteeped cotton fibers arei tr'eated with.

acrylonitrile in the vaporphase.

We have discovered asignificantrelationship between the concentration ofsodiumfhydroxide, the amountof water with respect to the cottonandflthe, acrylonitrile, and the temperature and time of treatment, ofthe cotton to form our improved ,cotton projduct efficiently, with aminimized lossof acrylonitrile through by-product formation. Ourinvention is based upon a control of the quantities of reactants and theconditions of treatment to form .cyanoethylated cotton having the{required nitrogen content and characteristic fibrous character ofnative cotton efficiently. The process of the invention'comprises, (1the 7 use of aerelatively low concentration,of sodiuni hydroxide intheaqueous solution'whichj results 'inlincreased reaction efiiciency, (2the use ot'ian .acc-uratelygcontrolled quantity of water in the emulsionwith "acrylonitrile to achieve uniform reaction with the cotton andminimize by-product formation; (3) the control of temperature and (4) acontrol of time in relation to the nitrogen content of the cotton.

One of the primary reaction variables is the sodium hydroxideconcentration. This should be kept as low as practicable, preferably inthe weight ratio of sodium hydroxide to cotton of from 0.005 to 0.10.The reaction efficiency, as used herein, is defined as the ratio of thetheoretical amount of acrylonitrile required to give the found nitrogencontent of the cyanoethylated cotton to the total amountnon-recoverable, expressed as a percentage. The non-recoverableacrylonitrile includes the acrylonitrile fixed by reaction with thecellulose, that reacting with the water to formbeta-beta-oxydipropionitrile (ODP) and other by-products. There is alsoa significant relation between the water concentrationin.the'emulsionand the temperature, the reaction efficiency increasing with a reductionin the water content, especially when this is accompanied by increasingtemperatures.

Several variables atfecting the nitrogen content of the cyanoethylatedcotton include variations in the temperature and in the amount of.sodium hydroxide based on the weight of the cotton. For example,withrespect to the sodium hydroxide efiect, the nitrogen contentof thecotton can be increased from "a mean of 2.48% to a mean of 3.02% whenthe weight ratio of sodium hydroxide to cotton is increased from 0.014to 0.021. With respect to the temperature effect, the-nitrogen contentof the cotton can be increased from a mean of'2.52% to atmean of 2.98%by increasing the reaction-temperature from 63 C. to.68 C. 'Ifthereaction time is constant, the two variables, sodium hydroxide contentand reaction temperature can'bechanged individually or togethertocontrol. the extent of cyanoethylation as indicated by the nitrogencontent; Advantageously, the reaction temperature should be :as high aspossible and reaction time as short as-.possible.

In its complete aspectsour invention comprises the circulation of anaqueous emulsion of sodium hydroxide solution in acrylonitrile while-incontact withsthe fibers of native cotton. in whichthetotal'water-phase,representing from 50% to 150% of the .weightofithe cotton, contains from0.50 to 10 percent .of sodium hydroxide at a temperature of from 24C..to 93? C. and .for from 1 to 360 minutes to cyanoethylate.preferentiallythe amor phous portion of the cellulose :to'such anextentthat the cotton contains from 0.5 to 6.5% .of nitrogen, the ratio of theweight of sodium hydroxide toathe..weight.of the cotton being from 0.005to 0.10. H v

In the accompanying drawings:

Figs. 1, 2 and 3 are curves showing the effects ofiyariations in thewater in the liquid phase .at different temperatures and sodiumhydroxide concentrations;

Figs. 4 and 5 are a series of curves showing the percentages of ODP withvariations in the sodium hydroxide,

temperature, time and Water in the liquid phase;

Figs. 6 and 7 are a series of cu'rvesshowing the effects of variationsin the sodium hydroxide in the liquid phase, with variations in thesodium hydroxide based on the cotton, water in the liquid phase, andtime.

The process of the invention may be carried out in any suitable kind ofequipment in which the emulsion of the aqueous sodium hydroxide solutionin acrylonitrile, at the proper temperature, is circulated in contactwith the cotton for a sufficient time to effect the reaction resultingin cyanoethylation of the cotton. The Gaston County package dyeingmachine which treats packages .of yarn in kiers is one suitable kind ofmachine for practicing the invention. a'Gaston County packaging machinecontaining 70packages of cotton yarn in the two kiers were treated ineach operation. The package'weights were usually one-pound, butthisvaried slightly from run to run. By winding the cotton yarn on'Davidsonsprings and compressing them to the maximum extent, it was: possibleto-putas much 98 pounds on the 70 packages. The ratio of the treating Inthe particular operations herein described,

components of the emulsion" tocotton c ould thusbe; varied over a widerange. Thefollowing representative operation was carried outwith 70packages of cottonyarn and is typical of the other operations whichwerecarried out under the variable conditions reported in the accompanyingdrawings. d I

I To 530 pounds of acrylonitrile contained in a circulating tankconnected to'the two kiers, a mixture of 1 pound of sodium hydroxide and0.5 pound of Aerosol-OS dissolved in 42pounds of water was added. Themixture was then circulated through a centrifugal pump, while agitationwas supplemented by the use of a Lightning mixer placed in the top ofthe circulating tank. After circulating for 30 minutes in this way atroom temperatu-re, an emulsion of the sodium hydroxide solution in theacrylonitrile was obtained. The two kiers of the package treatingmachine were then loaded with 67 pounds of cotton yarn containing 6percent moisture in the usual manner and after closing the kiers theemulsion of sodium hydroxide solution in acrylo'nit'rilef was pumpedthrough the packages at room temperature, 24 C., for 30 minutes. Thisresulted in a liquor to cotton ratio of 10.7 to 1. At the end of thistime the temperature of the liquor, while being continuously circulatedthrough the packages, was raised over a period of 5 minutes from 24 C.to 68 C. The rate of flow of the liquor through the packages wasapproximately 250 gallons per minute. 30 minutes, at 68 C., after whichthe liquor was cooled to room temperature and the sodium hydroxideneutralized with an aqueous phosphoric acid solution. The acrylonitrileremaining in the yarn in the kiers, of the package machine was thenremoved by washingwith water. It was found that about 90% of theacrylonitrile retained by the packages was removed by three charges ofwater weighing roughly 700 pounds each. These wash waters were collectedand, with thespent acrylonitrile liquors from the reaction, subjected toflash distillation for recovery of the unreacted acrylonitrile. The yarnpackages, after thorough washing in the package machine with water toremove all traces of acid and salts, were removed, centrifuged, andcarried to a package dry: ing unit, where warm air was blown throughthem until they were substantially dry. From the 7/1 cotton yarn treatedin this instance, 81 pounds of cyanoethylated cotton yarn, containing4.5% nitrogen, were obtained. Simultaneously, with the reaction ofacrylonitrile with cotton, the acrylonitrile also reacted with par-t of.the water present, so that 30 pounds of. acrylonitrile went intolay-product formation while 14 pounds of acrylonitrile were fixed on theyarn. This gave a ratio of acry lonitrile going into by-productformation to acrylonitrile fixed on the yarn of 2.1 to 1, or a reactionefiiciency of 32%. The effective initial caustic concentration wascalculated to be 2.1 percent and the ratio of caustic to cotton was0.016. d

In another example, 400 pounds of acrylonitrile containing 5.1 percentODP were placed in a circulating The circulation was continued for tankconnected to the kiers and a mixture of 3.65 pounds of sodium hydroxideand 0.5 pound of Aerosol-OS dissolved in 49 pounds of water added. Themixture was then circulated through a centrifugal pump while agitationwas supplemented by use of a Lightning mixer placed in the top of thecirculating tank. 7 After agitating for 30 minutes in this way at roomtemperature, an emulsion of the sodium hydroxide solution was obtained.One of the two kiers of the package treating machine was then loadedwith 38 pounds of yarn containing a 6' percent moisture in the usualmanner, whereas the other kier was cut out of the system. This resultedin a liquor to cotton ratio of 10.1 to 1. After closing the chargedkier, the emulsion of sodium hydroxide solution in acrylonitrile waspumped through the packages at room temperature, 24 C., for 30 minutes,reversing the direction of flow at 4-minute intervals.

At the end of this time the temperature of the liquor while beingcontinuously cir culated uthroughthe packages was raised over a periodof.

minutes at 38 C., after which the liquor was cooled to roomtemperatureand thesodium hydroxide neutralized with an aqueous phosphoric acidsolution. The packages of 7/1 yarn after thorough washing and drying, asdescribed above, weighed 45.4 pounds and upon analyzing were found tocontain 4.3 percent nitrogen. The spent liquor from the reaction sampledat the completion of the reaction contained 10.9 percent ODP. Thus 16pounds of 'acrylonit-rile went into by-product formation, while 7.4pounds were fixed to the yarn. This gave a ratio of acrylonitrile goinginto by-product formation to acrylonitrile fixed on the yarn of 2.2 to1, or a reaction efficiency of 31 percent. It will be noted that theeffective caustic concentration in this run was 7.1 percent in the waterphase of the emulsion initially, and the ratio of caustic to cotton was0.10.

A sample of yarn taken from the above run after the 30-minutecirculation of the treating liquor at 24 C. was freed of caustic andacrylonitrile by acid neutralization and water washing. After drying thecyanoethylated yarn had a nitrogen content of 2.2 percent, indicatingthat the reaction proceeds fairly rapidly during the circulation periodprior to raising the temperature to38 C.

The foregoing typical operations were carried out many peratures andvarying periods of treatment.

The curves of Figs. '1, 2 and 3 indicate'that the water and sodiumhydroxide approach and equilibrium between the liquid phase and thecotton during the first ten minutes of circulation. The waterconcentration of the liquid phase is reduced to about one-half itsoriginal amount while the sodium hydroxide concentration is reducedten-fold during the first ten minutes of circulation. When the mixturecontained 6 percent water at the beginning, the water content of theliquid phase approached the solubility limit of waterin acrylonitrile at24 C. (which was the approximate temperature maintained during coldcirculation).

As the reaction temperature was increased, the water" was dissolved inthe liquid phase. In the series of experiments performed with 6 percentwater in the liquid phase I at the'beginning, slightly more than 6percent appeared after the reaction mixture was heated. This is probablycaused either by water retained in the system or regain moisture in theyarn. With 8 percent water at the start, the liquid phase approached 8percent water content as a limit during reaction. At 10 percent, thelimiting factor for the water content during the reaction period was thesolubility of water in acrylonitrile, so the water content of the liquidphase did not approach 10 percentin this series. Increasing the sodiumhydroxide concentration from 0.014 lb. to 0.021 lb. per pound of cottonhad no apparent effect upon the distribution of water between the yarnand liquor phases.

The operations show that the variable that has the most effect uponreaction efficiency appears to be the sodium hydroxide concentration andthat it should be kept as low as possible for the desired nitrogencontent of the yarn. v

The data in Fig. 4 compare the rate of ODP formation for each operation.These data indicate that ODP formation is approximately linear withtime. At 6 percent water in the liquid phase there is little differencein GDP formation when other reaction variables are changed, although thehigher sodium hydroxide concentration is associated with the greatestODP formation.

At 8 percent water, the effects of both temperature and sodium hydroxideupon ODP formation are shown,

If either-reaction temperature or sodium hydroxideconacentration isincreased, the ODP formation isjalsoyincreasedfi i q At 10'percentwater, it is apparentthat the sodium hydroxide concentration has agreater effect upon ODP formation than reaction-temperature; since theslopes of the lines comparing ODP formation-at different sodium paringdifferent reaction itemperaturesfl j-InFig; 5 the percentage nltrogen"hydroxide concentrations arehigherithan thosecome esting to note thatthe nitrogen content ofthe yarn is decreased in most instancesas'thelwater inthe reaction was absorbed most rapidly from the highestsodium hydroxide concentration.

It may be concluded that the rate'and extent of cyano- I ethylation ofcotton may be realized alongwith a mini- 3 mum of ODPfby-productformation by'the proper control of the reaction variables of'time,temperature, initial caustic concentration in the. water phase of thecaustic solution-acrylonitrile dispersion, and the related final ratioof caustic to cellulose as well as the concentration of the waterphasein the acrylonitrile. p

The one-step cyanoethylation process of the invention results in (1)less handling costs in the. case of yarn treatment, (2)decreasedaby-productformation, (3) the use of .-water saturatedacrylonitrile .in the reaction, and (4) decreased the overall time. fortreatment. Each of these factors tends togimprove the economics of thecyanoethylation process,

This application is a continuation in-part of our patent applicationSerial No. 435,904, filed June 10,.1954, now abandoned.

We claim: p p

1. The process of treating native cottonfibers to effect but a partial.cyanoethylation of the cellulose and retain thenatural physical,structureof the cellulose which comprises circulatingin, contact .withsaid,fibers an emulsion of an aqueous solution of sodium hydroxide inacrylonitrile at a.temperaturelofffromabout24 C. to 93 C. and inwhichtthe ratio. of sodium: hydroxide to cotton by weight varies from0.005 to 0.100; and continuing the circulation until thecotton.isbcombined with such an amount of acrylonitrile that thenitrogen content thereof varies for different reaction. conditions from0.5% to 6.5% based on the weight of.the .cyanoeth'ylated cotton.

2. The process of claim:.1, wherein thecmulsion is circulated over thecotton :at .normal .room rtemperature fixed 'to the. yarn" andthe'amounty ofODP" in the spent'reaction. liquor formed in eachreactionis comparedwith the amount.

of water in the original reaction mixture." It ;is 'inter= foratimeupito about minutes'and then the; emulsion isfcrrculate overfthepottonat an elevated temperature P Y fl e'"pro'ce'ss"oftreatingnativecottonfibers to effect 'artial 3 cyanoethylation of thecellulose and retain the natural physicalstructure of the cellulosewhich com= prises circulating "ini'contact with saidfibers an emulsionof aniaqueous solution" of sodium hydroxide in acrylo nitrile," saictr'emulsion containing up tog12% of water withrespcctto'the'acrylonitrileand such an amount of sodium hydroxide thatthe ratio. of sodiumhydroxide to cotton variesfrom" 0.005 'to0.l0, the circulation beingcontinuedfora"suflicient time to combine withthe cotton such an amountofacrylonitrile that the nitrogen contentjthcreoffvaries-fordifferentreaction conditions from 0.5% to 6."5%'ba"sed"on the weight of thecyanoethylated cotton withjout producingmore than 10%oxydipropionitrile'as'a'by-product in the spent liquor.

4. Thepro'cess'oflclaim 3, wherein the circulation is continued up to20' minutes.

5. Thepro'cessof treating native cotton fibers to effect but a partialcyanoethylationof the cellulose and retain the natural physicalstructure of the cellulose which comprises circulating in contact withsaid fibers an emulsion of"an.aqueoussolution of sodium hydroxide inacrylonitrile'at a'temperature of from about 63 C. to 79f C.,

the ratio of the weight of sodium hydroxide to the weight sodiumhydroxide solution and acrylonitrile in which the water phase containsfrom 0.5 to 10.0% of sodium hydroxide, the ratio of the weight of sodiumhydroxide to the weight of the cotton being from 0.005 to 0.10,continuing the'reaction at a temperature of frorns62.8 C(to 79.4 C.until the amorphous portion of said fibers are cyanoethylated to such anextent that the cotton contains from 0.50 to 4.5% of nitrogen based onthe dry weight of the cyanoethylated cotton and in which substantiallyall of the original crystalline structure of the native cotton isretained, said cyanoethylated cotton having the appearance, hand andprocessing characteristics of the native cotton, increased abrasionresistance, in

creased tensile strength, decreased moisture absorptivity, and increasedalfinity for acetate, vat, and sulfur dyes.

References Cited in the file of this patent UNITED STATES PATENTSHanford June 2, 1942 MacGregor Sept. 13, 1949 Downey Feb. 3, 1953 UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,840,446 June24, 1958 Jack Compton et a1.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction and that the saidLetters Patent should read as corrected below.

Column 1, line 55, for "0.006" read -=0.06=-; column 8, line 59, list ofreferences cited, under the heading "UNITED S'IATES PATENTS", for thepatent number "2,482,001" read 2,482,0ll=v-=.

Signed and sealed this 7th day of October 1958.

WIFE. AXLINE ROBERT C. WATSON Attesting Ofiicer Commissioner of Patents

1. THE PROCESS OF TREATING NATIVE COTTON FIBERS TO EFFECT BUT A PARTIALCYANOETHYLATION OF THE CELLULOSE AND RETAIN THE NATURAL PHYSICALSTRUCTURE OF THE CELLULOSE WHICH COMPRISES CIRCULATING IN CONTACT WITHSAID FIBERS AN EMULSION OF AN AQUEOUS SOLUTION OF SODIUM HYDROXIDE INACRYLONITRILE AT A TEMPERATURE OF FROM ABOUT 24*C. TO 93*C. AND IN WHICHTHE RATIO OF SODIUM HYDROXIDE TO COTTON BY WEIGHT VARIES FCROM 0.005 TO0.100, AND CONTINUING THE CIRCULATION UNTIL THE COTTON IS COMBINED WITHSUCH AN AMOUNT OF ACRYLONITRILE THAT THE NITROGEN CONTENT THEREOF VARIESFOR DIFFERENT REACTION CONDITIONS FROM 0.5% TO 6.5% BASED ON THE WEIGHTOF THE CYANOETHYLATED COTTON.